You should plot the cm versus alfa for changing the point of moment calculation. You will see on one point the cm is approximatly constant. This point is aerodynamic center. You can start with .25 root chord.

Experimentally, aerodynamic balance might be the direct way to find the location of the aerodynamic center of a airfoil. If you have measured the pressure and the friction (always hard to measure) distributions, you might find the center by integrating these forces. Numerically doing is similar.

Hi, it depends on demanding accuracy. You can just say it is approx. 25 percent of chord or you can also use Xfoil. CFD and measurement is more sophisticated and it consumes more time. Then search for point, where moment coefficient is independent on angle of attack (cm should be constant, but it is working only in limited range of angle of attack). So, you need compute or measure more cases with different angle of attack.

There is a solution of your problem in a book fundamental of aerodynamics by john d. Anderson jr. So i suggest you to go through it.

You should plot the cm versus alfa for changing the point of moment calculation. You will see on one point the cm is approximatly constant. This point is aerodynamic center. You can start with .25 root chord.

For cambered airfoils the theoretical aerodynamic center is 0.25 of the cord length. For the exact value you should use CFD or wind tunnel test data.

Amir H. Nikseresht , Dear sir, I got the same task of finding the aerodynamic center of cambered aerofoil. Either CFD or Experimentation requires more work and time. Will you please suggest any tool that can perform this task.